Cabling - how to avoid interference problems

Guest

I am just about to transfer the mess of units and cable that adorns one corner of my living room onto a brand spanking new, top of the range AV stand.

I am lucky enough to own some very expensive, (very thick, heavy and inflexible) cables. The new stand provides various cable management options including seperate ducting and running cables through the hollow legs.

What are the dangers of interference in this? Should I run power cables through the same ducting? If I run, say, two component cables, two HDMI cables, an optical digital cable all crammed tight together in a metal tube, won't they interfere with each other? What about if I run a mains cable in there too?

I would love to see some clear guidelines on this. None of the stand or cable manufacturers I've spoken to will commit themselves. Does anyone know? Can anyone help?

Please please, please!

(Question 2 - Why aren't cables for interconnects produced in very short lengths? 30 cm or 50 cm component or HDMI cables would be perfect for patching my source components into my AV receiver)